This application relies for priority upon Korean Patent Application No. 2000-27743, filed on May 23, 2000, the contents of which are herein incorporated by reference in their entirety.
1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a very small-sized memory card for storing and retrieving data for digital products.
2. Description of the Related Arts
Recently, various digital products such as MP3 phones, MP3 players, or digital cameras have been developed and becoming widely used. These digital products use a memory card to store and retrieve data. The memory card typically employs flash memory chips, newly introduced as storage media.
FIGS. 1 and 2 show a conventional memory card 10, where a semiconductor package 20 is contained in a plastic card base 30, a xe2x80x9cbase cardxe2x80x9d. The semiconductor package 20 is a COB (chip on board) package. The package 20 is physically attached to the card base 30 with a double-sided adhesive tape 32.
The memory card 10 is inserted into the digital products (not shown). A plurality of external contact pads 26 exposed on the surface of the memory card 10 are connected to the digital products to provide electrical connection between the memory chip 10 and the digital products. Because the external contact pads 26 are exposed on the outside of the memory card 10, the external contact pads 26 can be easily contaminated by dust or other contaminants during the actual usage. Therefore, the memory card 10 needs a holding portion 12 to be grasped by the user. However, this increases the size of the memory card 10. The external contact pads 26 are not formed on the holding portion 12.
The memory card 10 has a size of approximately twice the total dimension of the external contact pads. For example, the size of the conventional memory card 10 is approximately 37 mmxc3x9745 mm. The size of the memory card prevents the miniaturization of digital products using the memory card 10, and further limits the development of portable electronic appliances such as a hand-held computer or a cellular phone.
The conventional memory card 10 is very thin, i.e. approximately 0.76 mm. This makes it difficult to mount the memory chip inside of the package 20. Further, it results in poor warpage resistance, and damage to the memory chip mounted within the package 20. Moreover, insertion or removal of the memory card 10 in and out of the digital products has been cumbersome, and the use of the memory card 10 has been restricted due to the poor thermal resistance thereof.
Further, the conventional memory card 10 has another problem in forming the molding resin layer 24 shown in FIG. 2. In particular, as illustrated in FIG. 3A, for forming the COB package 20, a memory chip 28 is mounted on a substrate 22 to be sealed by a molding resin 24. The molding resin layer 24 for hermetically sealing and protecting the memory chip 28 is generally formed by a molding method using a mold 40 shown in FIG. 3A. The substrate 22 with the memory chip 28 is placed in the mold 40. Then, a liquid molding resin is injected into the mold 40 and cured. Accordingly, as shown in FIG. 3B, the molding resin layer 24 is formed. Then, molding resin residue 46 on a gate 44 is removed. However, it is not easy to thoroughly remove the molding resin residue 46 due to strong adhesion between the molding resin 42 and the substrate 22.
In order to solve the above-stated conventional problem, as shown in FIG. 3C, in U.S. Pat. No. 5,780,933 and U.S. Pat. No. 6,022,763, a plating layer 48 is formed on the substrate 22 in a predetermined area. By using the plating layer 48, the molding resin residue 46 can be easily removed from the substrate 22 compared to the conventional methods. However, even with this method, the molding resin residue 46 still remains. The remaining molding resin residue 46 prevents the adhesion between the card base 30 and the package 20.
Accordingly, there is a need to develop a new memory card and a semiconductor package structure and method of manufacturing thereof to overcome these problems.
Accordingly, an object of the present invention is to provide a memory card having a reduced size enough to realize the miniaturization of the digital products.
Another object of the present invention is to provide a memory card having new types of external contact pads for preventing the contamination.
Still another object of the present invention is to handle the memory card easily and improve its reliability.
Further, another object of the present invention is to form the molding resin layer, on which the molding resin residue does not affect the adhesion between the card base and the package.
In order to achieve the foregoing and other objects, the present invention provides a memory card having a reduced size to that of the package, the memory card comprising the electrical contact pads formed on one end in a single row.
The memory card of the present invention comprises a card base and a semiconductor package. The card base comprises a first surface and a second surface, the first surface having a cavity formed thereon. The semiconductor package comprises a substrate, memory chips, and a molding resin layer, and is mounted on the cavity so that the external contact pads are exposed. Circuit wirings are formed on an inner surface of the substrate and the external contact pads electrically connected to the circuit wirings are formed on an outer surface of the substrate. The memory chips mounted on said substrate, and the memory chips are connected to the circuit wirings by an electrical connection means. The molding resin layer hermetically seals the memory chips and the electrical connection means.
Preferably, a slot is formed on the second surface of the card base, and the semiconductor package is mechanically attached to the cavity by a liquid adhesive. The memory chip is NAND-type or NOR-type flash memory chip, and the electrical connection means between the memory chip and the circuit wirings is selected from the group consisting of a metal wire, a TAB tape and an anisotropic conductive film (ACF). It is preferable that the molding resin layer is asymmetrically formed so that the molding resin layer is biased to an edge opposite to the edge on which the external contact pads are formed, and that the molding resin layer comprises a notch corresponding to a gate. The notch indents into the molding resin layer horizontally from an edge of the molding resin layer and downwardly from a top surface of the molding resin layer